Speedometer



Dec. 2, 1930.

R. O. HELGEBY.

SPEEDOMETER Filed Aug. 20. 192.8

Patented Dec. 2, 1930 I UNITED STATES PATENT OFF-ICE RALPH o. HELGEIBY,or FLINT, MICHIGAN, ASSIGNOR TO A C SPARK PLUG COMPANY, 01?

FLINT, MICHIGAN, A COMPANY or MICHIGAN SPEEDOMETER Application filedAugust 20, 1 928. Serial No. 300,847.

This invention relates to magnetic measuring instruments and has beendesigned more 7 'partlcularly'to provide an improvement in a'fixedmagnettype of speedometer for vehicles.

An object of the invention is to provide a clamping means by which aU-shaped magnet may be quickly mounted on the instrument frame.Simplicity, efiiciency, conveniencein assembly and economy are among theobjects sought to be attained- In the drawing: Figure 1 is a top planview of a speedometer employing a permanent fixed magnet held inposition by my novel clamping means; Figure 2 is a side elevation of thesame; and Figure 3 is a perspective of the clamp. Referring by referencecharacters to the several figures of the drawing, numeral 15 designatesan instrument frame for carrying the parts constituting the speedindicating mechanism. It is also designed to carry the odometermechanism, although the latter is in no way concerned with thisinvention. The

frame is preferably die cast. It maybe formed with a bearing 21 for thereset stem ofthe odometer. "Across the top of the frame is a jewel frame22 secured by suitable fastening means 23 to themainframe 15. At "24, isa conventional speed cup, its zero reading being assured by hair spring25. This hair spring is operative-1y associated with a spindle, notshown, carrying the speed cup and with an arm 26 on an adjustableregulator 27, which is rotatable about an upper bearing carrier28 forthe saidspindle. The jewel frame 22 has stampedtherefrom a part 22'positioned over. the said SPlIldlBllO retain the same from axialmovement. The

lower bearingfor the spindle is, as is customary in such constructions,located in the upper endof the rotor shaft, not shown.

This rotor-shaft is mounted in the frame 15 and is, as usual, driven bya flexible shaft,

not shown. The rotor shaft as usual terminates in a rotor located withinthe speed cup. A magnet 14 surrounds the speed cup, rests upon and isclamped to the frame. To hold the magnet in position, there is used thenovel attachment which constitutes the subject of to engage the frame.is tightened, it draws up the magnet firmly this application. Thisattachment comprises a clamp designated as a whole by numeral 9,

the clamp being preferably made as a stamp-;

into position on the frame, the legs 10 and 11 being arcuately bent toengage the peripheral surface of the magnet and the fingers 12 and 13gripping the upper edge thereof to restrain the magnet from movement.

There has thus been designed a simple, effective clamp of substantiallyY-shape. This clamp is economical to manufacture and it provides foraneasy assembly of the U-shaped magnet on the die cast frame.

lrIn a measuring instrument, a frame, a U-shaped magnet supportedadjacent the ends,

of its legs on said frame and the end faces of said legs engagingsaidframe, a clamp of substantially Y -shape, two legs of said clampembracing said magnet between its ends, a third leg abutting said frame,and fastening means engaging a middle part of said clamp andiadjustablysecured to said frame.

2. The invention defined by claim 1, said first-mentioned legs havingangularly positioned terminal fingers engaging the upper surface of saidmagnet.

3. The invention defined by claim 1, said first-mentioned legs being ofarc shape to conform to the shape of said magnet and having angularly'positioned terminal fingers I engaging theupper surface of saidmagnet..- In testimony whereof I affix my signature- RALPH O. HELGEBY;

